DS3231 I2C

Implementation

The library implements 2 structures: struct mgos_ds3231 and a helper struct mgos_ds3231_date_time.
Both structures are available for mJS too. The mJS support is available if the user includes the mjs library:

- origin: https://github.com/mongoose-os-libs/mjs

struct mgos_ds3231

This is used to communicate with the DS3231.
The RTC data is read into and written from using the helper struct mgos_ds3231_date_time